Bubbles after second firing or glaze baking using NP metal

[martintay]

Oh i see - i wear latex gloves , the same as dentists use !

 

[rod]

Greetings all, Perhaps someone can pinpoint the problem Ive been experiencing for the last few months.

1)Porcelain: Noritake EX-3. Alloy:Bego wirobond 280.
2)Slight greening in crucible from previous casting.
3)Ingot melting time and technique duplicated and mimicked as indicated on Bego website video.
4)Only New metal used.
5)Tried both 110 pu and 250 pu grain for sandblasting
6)Steam cleaned
7)Then Ultrasonically cleaned copings for 5-7 mins
8)Air-dried completely before application of POBA (paste opaque base)--->2 bakes
9)Applied same thickness of Shade opaque as required for Semi-Precious alloys--->1 bake
10)Increased recomended manufacturers drying time by 2 mins
11)Decreased start temperature to 400 degrees C. as per Noritake troubleshooting guide
12)Tried to purge 2 furnaces with carbon to aid in chamber de-contamination.

Problem persists... IRREGULARLY!!! Hit or miss. Bubbles appear after 2nd body bake or glaze bake, particularly common around margin area (thin porcelain area).

I am about to change all burs for metal finishing (once again) to make absolutely certain that there is no cross contamination.

Does anybody have any other suggestions to fix this problem after all of those steps are performed and problem persists?

A solution would be greatly appreciated!!!!

well
i recomend you to use a kind of bonding after sandblasting
BREDENT has a wonderfull one,i can sure if you use it,you won't see no more bubbles
be clean,sandblast,bonding,opaque.
that's all,
let's see what happens
see the link below

http://www.bredent.com/en/bredent/product-group/10547/page/1/

 

[martintay]

Yes Rod i was going to mention the Bredent one - it does the same job as the GC-In MB that i was talking about

 

[2oothguy]

Greetings all, Perhaps someone can pinpoint the problem Ive been experiencing for the last few months.

1)Porcelain: Noritake EX-3. Alloy:Bego wirobond 280.
2)Slight greening in crucible from previous casting.
3)Ingot melting time and technique duplicated and mimicked as indicated on Bego website video.
4)Only New metal used.
5)Tried both 110 pu and 250 pu grain for sandblasting
6)Steam cleaned
7)Then Ultrasonically cleaned copings for 5-7 mins
8)Air-dried completely before application of POBA (paste opaque base)--->2 bakes
9)Applied same thickness of Shade opaque as required for Semi-Precious alloys--->1 bake
10)Increased recomended manufacturers drying time by 2 mins
11)Decreased start temperature to 400 degrees C. as per Noritake troubleshooting guide
12)Tried to purge 2 furnaces with carbon to aid in chamber de-contamination.

Problem persists... IRREGULARLY!!! Hit or miss. Bubbles appear after 2nd body bake or glaze bake, particularly common around margin area (thin porcelain area).

I am about to change all burs for metal finishing (once again) to make absolutely certain that there is no cross contamination.

Does anybody have any other suggestions to fix this problem after all of those steps are performed and problem persists?

A solution would be greatly appreciated!!!!

Make sure you are using enough air when you cast, this will cause problems for you in the porc dept if you dont. We cast with 40lb of air and 2lb of gas for non. . Also sandblast with 50 micron alum ox. We rinse off copings and place in ultra sonic for a min of 10 min. Then towel dry and degas. We use ceramco ultra paste with powder. Check your crucible may need a new one? If using a new one just heat it up and get a good glaze on it. Dont add any thing to it like some paste products or anything like it. no need Also make sure your casting machine and surrounding areas are clean every time before you cast. Just a quick wipe down. Also try a different kind of carbon my experience is that a few brands we used made matters worse.

 

[Hary]

Greetings all, Perhaps someone can pinpoint the problem Ive been experiencing for the last few months.

1)Porcelain: Noritake EX-3. Alloy:Bego wirobond 280.
2)Slight greening in crucible from previous casting.
3)Ingot melting time and technique duplicated and mimicked as indicated on Bego website video.
4)Only New metal used.
5)Tried both 110 pu and 250 pu grain for sandblasting
6)Steam cleaned
7)Then Ultrasonically cleaned copings for 5-7 mins
8)Air-dried completely before application of POBA (paste opaque base)--->2 bakes
9)Applied same thickness of Shade opaque as required for Semi-Precious alloys--->1 bake
10)Increased recomended manufacturers drying time by 2 mins
11)Decreased start temperature to 400 degrees C. as per Noritake troubleshooting guide
12)Tried to purge 2 furnaces with carbon to aid in chamber de-contamination.

Problem persists... IRREGULARLY!!! Hit or miss. Bubbles appear after 2nd body bake or glaze bake, particularly common around margin area (thin porcelain area).

I am about to change all burs for metal finishing (once again) to make absolutely certain that there is no cross contamination.

Does anybody have any other suggestions to fix this problem after all of those steps are performed and problem persists?

A solution would be greatly appreciated!!!!

Hi, try to get rid of the number 6 step and number 8 and after ultrasonic put your metal copings in a kleenex and try not to touych with your fingers after oxidation it will be best to hot plate your opac. I hope that will resolve your problem.

 

[Edy]

I had the same problem with ex3 , i changed my burs , and i switched the paste opaque of ex3 to vita master powder opaque , i get much better results with almost no bubbles , but from now and then i still got them , i really dont know , maybe i need to try another alloy , used inline before with no such problems of bubbles

 

[rod]

I had the same problem with ex3 , i changed my burs , and i switched the paste opaque of ex3 to vita master powder opaque , i get much better results with almost no bubbles , but from now and then i still got them , i really dont know , maybe i need to try another alloy , used inline before with no such problems of bubbles

I use noritake ex3 too,a very stable porcelain,
but again:-BE CLEAN
-SANDBLAST
-ULTRASONIC
-USE BREDENT BONDING
try it,and tell us what you got

http://www.bredent.com/en/bredent/pr.../10547/page/1/

and so look at your CET's: alloy and ceramic

don't go around

 

[Tayebdental]

I never had a problem with noritake ex3 bubbling, using it for 19+years,I use tungeston carbide burs to finish metal, sand plast and ultrasonic clean in a glass jar filled with acetone for 5 min it completely eliminates any traces of oils. I use paste opaque on noble alloy, degas,1st wash opaque, 2nd and final opaque application.

 

[Marcia14]

When was the last time you changed the tip on your sandblaster? It was the last thing I thought of...and it solved my problem.

 

[Edy]

Well well , i was so pleased that i didnot had those bubbles like more then 2 months , and we talk about it and vualaaa , here are they appear again , in this case after 2 bakes i had only one small bubble , made a correction third bake and i just fall out of chair when i saw these , all over the place , i sandblast , ultrasonic , and opaqued like in the book , but still this is the end result,you can see the big ones , in the camera the smaller once are not so clear , but many small bubbles too , i need to strip everything now and build these for tomorrow , sigh man .

 

[ztech]

Looks like a metal gassing problem. If you grind on these and they go to the opaque, look for a small pinhole in the opaque. If that is present then the problem most likely is within the alloy.

 

[Tayebdental]

Looks like a metal gassing problem. If you grind on these and they go to the opaque, look for a small pinhole in the opaque. If that is present then the problem most likely is within the alloy.

After grinding the bubble if you see metal, it is serface contamination on the metal, use only smooth carbide on straight hand piece to finish the metal and away from stones and binders. Also casting prosedure is of extreme importance if using torch!!!.

 

[rkm rdt]

It's not your opaque.

I only use a carbide on ceramic gold alloys and I only use stones on semi precious alloys ( silver palladium)

The metal surface may be too rough and air is being trapped when you apply the opaque.

After you bake the opaque,inspect it under a microscope and you will see any bubble trouble before you fire any porcelain.


By the way ,I don't degass any alloy after trimming the metal. I just sandblast the alloy and apply the opaque (one layer) and fire.

 

[Edy]

After grinding the bubble if you see metal, it is serface contamination on the metal, use only smooth carbide on straight hand piece to finish the metal and away from stones and binders. Also casting prosedure is of extreme importance if using torch!!!.

that may be my problem , maybe i burn the metal while casting ? and thats why i got these bubbles ?

 

[Ivan]

My brother-inlaw had a similar problem. He tried everything. Finally discovered that his compressor was blowing oil. He got a new compressor. Problem fixed!

 

[Tayebdental]

that may be my problem , maybe i burn the metal while casting ? and thats why i got these bubbles ?

Edy,
I know induction machines are expensive, but they do an excellent job when it comes to density and predictability on the results with the alloy every time. Beside that any body could do the casting with minimal training. Where you are, the Italians make a reasonably priced good induction casting machine " I think called galloni" good luck!

 

[rkm rdt]

He's trapping air in his metal

 

[martintay]

So many possibilities as to what the problems are _ such is the life of a dental tech. it can be very flustrating

 

[settimius]

Edy,
I know induction machines are expensive, but they do an excellent job when it comes to density and predictability on the results with the alloy every time. Beside that any body could do the casting with minimal training. Where you are, the Italians make a reasonably priced good induction casting machine " I think called galloni" good luck!

Yes,there are Galloni,Manfredi for induction casting,very good also the french Ugin dentaire

 

[Tayebdental]

He's trapping air in his metal

I think, casting and finishing are the problem, if the wrong bur is used as you said it will create scales that trap not just gases but contaminant and tiny particles that do not belong there!!!.